Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
  • F02M59/20—Varying fuel delivery in quantity or timing
  • F02M59/34—Varying fuel delivery in quantity or timing by throttling of passages to pumping elements or of overflow passages, e.g. throttling by means of a pressure-controlled sliding valve having liquid stop or abutment
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/30—Controlling fuel injection
  • F02D41/38—Controlling fuel injection of the high pressure type
  • F02D41/3809—Common rail control systems
  • F02D41/3836—Controlling the fuel pressure
  • F02D41/3845—Controlling the fuel pressure by controlling the flow into the common rail, e.g. the amount of fuel pumped

Definitions

• Fuel delivery device in particular for an internal combustion engine
• the invention relates to a fuel delivery device, in particular for an internal combustion engine, according to the preamble of claim 1.
• DE 10220 281 A1 describes a fuel system for an internal combustion engine, in which
• Fuel is conveyed from a prefeed pump to a high-pressure pump and from there into a high-pressure fuel rail. To this several injectors are connected, which inject the fuel directly into combustion chambers of the internal combustion engine.
• the flow rate of the mechanically driven by the engine high pressure pump is effected by a fluidically upstream throttle device. To limit the production effort, is the
• Throttle device designed so that it even in completely closed state through a certain amount of leakage of fuel. This is returned to a low-pressure region via a zero-delivery line, in which a zero-feed throttle is present, so it does not reach the actual piston pump.
• the present invention has the object, a fuel delivery device of the type mentioned in such a way that it builds as simple as possible.
• a special leakage pump means is provided by the leakage amount at least partially from the working space to an upstream of the Throttle device located low pressure range is conveyed away. This may for example be immediately upstream of an inlet valve of the piston pump, so that the fuel delivery device is very compact and additional long lines are not required.
• the leakage pump device can be realized by the pump piston of the piston pump itself and the guide gap between the pump piston and the pump housing.
• Leakage amount is simply removed in this case by the pressure difference between the working space and the drive side of the pump piston. In this case, a good efficiency of the fuel delivery device is maintained when the guide gap is formed so that when the throttle device is closed, just the leakage amount of the throttle device is conveyed back to the low pressure area.
• the fuel delivery device usually conveys into a high-pressure space, for example a high-pressure rail.
• a high-pressure space for example a high-pressure rail.
• this can be connected via a fluidically parallel to an outlet valve of the piston pump throttle with the working space of the piston pump. In this way, it is possible to dispense with a separate pressure relief valve on the high-pressure chamber, which further simplifies or reduces the construction and the corresponding costs of the fuel delivery device according to the invention.
• the opening differential pressure of an inlet valve of the piston pump is at least about 1 bar, since in this case the formation of fuel vapor due to pressure pulsations during operation of the piston pump between the throttle device and the inlet valve is prevented.
• the leakage amount is kept low overall by a control opening is not present at the throttle valve but at the throttle body at a throttle device with a throttle slide.
• the guide gap between throttle slide and throttle housing should be less than or equal to the guide gap between pump piston and pump housing. Typical values are 4 or 7 ⁇ m.
• the leakage quantity of the throttle device should be smaller than the fuel requirement of an internal combustion engine when idling, ie if only a minimal amount of fuel is injected into the combustion chambers of the Brennkrafhnaschine.
• FIG. 1 is a schematic representation of a first exemplary embodiment of a fuel
• Figure 2 is an enlarged view of a portion of the fuel delivery device of Figure 1;
• Figure 3 is a diagram in which a pressure difference across a pump piston of the conveyor of Figure 1, a piston stroke and a leakage amount of a
• Throttle device are applied over the angle of a drive shaft
• Figure 4 is a view similar to Figure 1 of an alternative embodiment of a
• Figure 5 is an enlarged view of a portion of the fuel conveyor of
• a first embodiment of a fuel delivery device bears the reference numeral 1 as a whole. It comprises a fuel reservoir 2 from which a prefeed pump 3 conveys the fuel via a line 4 to a high-pressure pump unit 10.
• the throttle device 20 is fluidly arranged between the prefeed pump 3 and the high-pressure piston pump 6, and it regulates the low pressure side, the flow rate of the high-pressure piston pump 6.
• the latter is in the present embodiment via a cam 30th driven, which in turn is mechanically driven in a manner not shown in Figure 1 by an internal combustion engine 7, for example, from the cam or crankshaft.
• the cam 30 may also be part of the cam or crankshaft.
• the high-pressure piston pump 6 compresses the fuel supplied to a relatively high pressure and delivers it via a line 5 in a high-pressure chamber 40.
• the fuel is stored under high pressure, it is also "high-pressure accumulator" or
• a plurality of injectors 41 are connected, which inject the fuel directly into each associated combustion chambers 42.
• the pressure prevailing in the high-pressure chamber 40 is detected by a pressure sensor 43.
• the speed of a not shown crankshaft of the engine 7 is detected by a speed sensor 44, a temperature of the engine 7 via a temperature sensor 45.
• a control and regulating device 46 controls or regulates inter alia the operation of the throttle device 20, wherein in the control or Control the signals of the sensors 43, 44 and 45, and possibly also other sensors, flow.
• a computer program for controlling the throttle device is stored on a storage medium 47 of the control and regulating device 46.
• FIG. 2 in which the high-pressure pump unit 10 is shown enlarged.
• a filter 101 is disposed in the high-pressure pump unit 10 and a pressure damper 102 is arranged in a channel 8 belonging to a low-pressure region.
• pulsations of the high-pressure piston pump 6 are to be damped, for example, in the line 4.
• the throttle device 20 comprises a cylindrical throttle slide 201 and a cylindrical throttle housing 202.
• the throttle slide 201 is actuated by an electromagnetic actuator 203, against which the throttle slide 201 is acted upon by a compression spring 204.
• the throttle valve 201 has a smaller diameter portion (not numbered) through which an inlet space 205 is formed between the throttle valve 201 and the throttle body 202.
• a circumferential control edge 206 is present, which cooperates with control openings 207 formed on the throttle housing 202. Via a connection 208, these lead to the high-pressure piston pump 6.
• a guide gap 209 is present between the throttle slide 201 and the throttle housing 202.
• the high-pressure piston pump 6 in turn comprises an inlet valve 103, via which the fuel can pass from the connection 208 of the throttle device 20 to a working space 104 which is formed between a pump piston 105 and a pump housing 106.
• the pump piston 105 is connected to a drive space in which the cam 30 is disposed via a
• Piston seal 107 sealed. From the working space 104 to the high pressure chamber 40, the fuel passes through an outlet valve 108. Parallel to this, but with opposite opening direction is between the working space 104 and high-pressure chamber 40 a Pressure relief valve 109 is arranged. This is closed during normal operation of the fuel conveyor 1.
• a bypass valve 110 is still arranged in the high-pressure pump unit 10, which connects the high-pressure chamber 40 with the located between the filter 101 and pressure damper 102 channel 8 and opens to the high-pressure chamber 40.
• This bypass valve 110 is closed during normal operation. In the event of a fault, for example, when the throttle device 20 is stuck in the closed position, however, fuel can pass into the high-pressure chamber 40 via this bypass valve 110, so that at least the pressure generated by the prefeed pump 3 prevails therein, which allows a certain emergency operation of the internal combustion engine 7.
• a guide gap 111 is present between the pump piston 105 and the pump housing 106.
• a leakage line 112 which leads to the low pressure region 8 immediately upstream of the filter 101.
• the mouth of the leakage line 112 is therefore covered by the pump piston 105, whereas the coming of the inlet valve 103 into the working space 104 and the outgoing from the working space 104 to the outlet valve 108 mouth of the pump piston 105 are always free.
• the prefeed pump 3 In normal operation, the prefeed pump 3 generates a prefeed pressure in the amount of about 6 bar. Depending on the position of the throttle slide 201 of the throttle device 20 and depending on the corresponding coverage of the control edge 206 with the Steueröfihungen 207 passes more or less fuel to the high-pressure piston pump 6. During the suction phase, the fuel is sucked into the working space 104 via the inlet valve 103. Depending on the throttling, more or less steam is produced in the working space 104. In this way, the delivery rate of the high-pressure piston pump 6 is set to the high-pressure chamber 40.
• the throttle device 20 is "normally closed", which means that the throttle slide 201 is pressed in the closed position with electroless electromagnetic actuator 203 of the compression spring 204.
• its opening differential pressure is about 1 bar.
• the opening differential pressure can also be significantly smaller. Even in the closed position of the throttle device 20, however, fuel can pass through the guide gap 209 between throttle slide 201 and throttle housing 202 and on via the inlet valve 103 in the working space 104 of the high-pressure piston pump 6.
• this quantity of fuel also referred to as "leakage quantity”
• this quantity of fuel is removed from the working space 104 via a leakage pump 113 conveyed away.
• this leakage pump device 113 is formed simply by the pump piston 105 and the guide gap 111 between pump piston 105 and pump housing 106. This is in fact dimensioned so that in a delivery stroke of the pump piston 105 just reached when the throttle device 20 into the working space 104 leakage fuel quantity due to the pressure difference between the working space 104 and the prevailing directly before the piston seal 107 prefeed over the
• Leakage line 112 is conveyed away. Functionally, the previously known "zero-feed throttle" is thus formed by the guide gap 111.
• FIG. 2 shows the course of the leakage flow through arrows 114.
• the functional principle of the leakage pump device 113 can also be seen from the diagram of FIG. It can be seen that in each case in the region of the top dead center of the pump piston 105 (the stroke of the pump piston 105 is represented by the curve 115) in the working space 104, a "pressure mountain" is formed (curve 116). A zero promotion of the high pressure piston pump 6 is present when the maximum pressure of this pressure mountain is at most equal to the current pressure in the high pressure chamber 40. This is only guaranteed if the total amount of leakage that is passed by the throttle device 20, from the leakage pump 113th is dissipated. Otherwise, the pressure in the working space 104 would increase with each cycle of the high-pressure piston pump 6 until the outlet valve 108 finally opens.
• the amount of leakage discharged from the leakage pump device 113 via the guide gap 111 is represented by the curve 117. It can be seen that, in the case of the high pressure prevailing in the region of top dead center, a relatively large amount of leakage passes through the guide gap 111 and is discharged from the leakage line 112. Outside the top
• dead center of the pump piston 105 prevails in the working space 104 partly a lower pressure than in the channel or low pressure region 8, so that even a certain, but very small amount of fuel flows back through the guide gap 111 into the working space 104.
• a typical vote is that the guide gap 111 has a value of 7 microns, the guide gap 209, however, has a value of 4 microns.
• the leakage amount of the throttle device 20 should be smaller than the fuel demand of the engine 7 in the idle. This is due to the fact that at such a low pressure in the high pressure chamber 40, the outlet valve 108 opens even at a correspondingly low pressure, so that the maximum pressure in the working chamber 104 also corresponds at most to the reduced pressure in the high pressure chamber 40. With such a However, the reduced pressure also decreases the pressure difference across the guide gap 111, which reduces the "delivery rate" of the leakage pump device 113.
• this leakage quantity should at most correspond to the fuel demand of the engine 7 when idling.
• the pressure in the high-pressure chamber 40 can be lowered by injecting more fuel from the injectors 41 into the combustion chambers 42 than by the fuel delivery device 1 into the high-pressure chamber 40. This can be adjusted by means of the throttle device 20. It is understood that the maximum pressure in the high-pressure chamber 40, which adjusts itself in the overrun mode of the internal combustion engine 7, should in principle not be greater than a pressure at which the injectors 41 are still working reliably. If such a lowering of the pressure in the high-pressure chamber 40 is not possible, this must be compensated by a correspondingly changed control of the injectors 41.
• the pressure in the high pressure chamber 40 is limited by the pressure relief valve 109 to a certain maximum value.
• the guide gap 111 operates as a flow restrictor between the working space 104 and the leakage line 112. Conceivable, but not shown, but is also that the leakage line branches off directly from the working space 104 and in her a separate flow restrictor is present, which takes over the hydraulic function of the guide gap 111.
• the guide gap 111 operates as a flow restrictor, this has the advantage that a variable throttling action can be realized which is lowest at bottom dead center of the pump piston 105 and greatest at top dead center.
• FIGS. 4 and 5 An alternative embodiment of a fuel delivery device 1 is shown in FIGS. 4 and 5.
• FIGS. 4 and 5 An alternative embodiment of a fuel delivery device 1 is shown in FIGS. 4 and 5.
• elements and areas which equivalent functions to elements and areas described in connection with Figures 1 to 3 Embodiment, have the same reference numerals. They are not explained again in detail.
• the delivery rate of the prefeed pump 3 can be adjusted. In this way, the pressure in the line 4 and in the
• Low pressure range 8 can be set according to a desired form.
• the prefeed pump 3 is controlled by the control and regulating device 46. This has the advantage that the prefeed pump 3 is always operated with the lowest possible power.
• an adjustable pre-pressure has the advantage that the control sensitivity of the throttle device 20 is improved.
• the pressure difference at the throttle device 20 can be adjusted optimally with adjustable admission pressure as a function of load and speed of the internal combustion engine 7. In addition, an increased fuel temperature or a higher vapor pressure can be compensated.
• a variable pre-pressure can also be used to reduce the amount of leakage
• Throttle device 20 and thus the self-adjusting high pressure in the high pressure chamber 40 to control or regulate. If, for example, the intake pressure is lowered in the overrun mode of the internal combustion engine 7, the leakage quantity of the throttle device 20 is also reduced, since the pressure difference at the guide gap 209 decreases to the same extent. With smaller leakage amount at the guide gap 209 of the throttle device 20 is in overrun the
• Internal combustion engine 7 also a lower pressure in the high-pressure chamber 40 a. Conversely, this means that with an adjustable form the requirements for the throttle device 20 can be reduced in terms of control sensitivity and allowable leakage amount. Thus, e.g. the guide gap 209 are increased, whereby the production is simplified.
• a flow throttle 118 is arranged parallel to the outlet valve 108. This allows a "passive" pressure reduction in the high-pressure chamber 40. In overrun the
• Internal combustion engine 7 or when stopped internal combustion engine 7 can be reduced in this way via the flow restrictor 118 and the guide gap 111 of the high pressure piston pump 6, the pressure in the high pressure chamber 40 to the pressure prevailing in the low pressure region 8 pressure.
• the pressure in the high-pressure chamber 40 can be lowered to a desired value and regulated by means of the variable admission pressure so that it is ideal for resuming the injection of the injectors 41.
• the fuel delivery device comprises a high-pressure piston pump with a plurality of pump pistons and work spaces arranged fluidically parallel to one another. Also in this case, the metering of the fuel can take place via a throttle device.
• the guide gaps When designing the guide gaps, however, the guide gaps of all pump pistons must be taken into account.

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Citations (5)

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• 2005
  • 2005-07-19 DE DE102005033638A patent/DE102005033638A1/de not_active Withdrawn
• 2006
  • 2006-05-29 CN CNA2006800263320A patent/CN101223353A/zh active Pending
  • 2006-05-29 DE DE502006004328T patent/DE502006004328D1/de active Active
  • 2006-05-29 WO PCT/EP2006/062671 patent/WO2007009829A1/de active Application Filing
  • 2006-05-29 US US11/910,328 patent/US7527035B2/en not_active Expired - Fee Related
  • 2006-05-29 EP EP06763329A patent/EP1913255B1/de not_active Expired - Fee Related
  • 2006-05-29 JP JP2008521912A patent/JP2009501867A/ja not_active Withdrawn

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